Correct ACG value for magnetic filament sensor?

[Nuffe]

I just installed new magnetic filament sensor. I was able to get it working initially, but calibration is starting be a problem. From other threads I noticed acg value should not be too high. What is the suitable value? For me it says 105-110. I purchased it together with the housing, I have not done anything for it except connected it.

It is currently disable, because it was pausing the print all the time.

Current data for the ongoing print (which had one heater fault due sock being off, and later sensor not working error) looks like this:

3/23/2020, 4:19:54 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 128 agc 105, measured sensitivity 31.52mm/rev, min -473% max 561% over 9584.5mm
Printing paused
Extruder 0 reports sensor not working
3/23/2020, 4:05:34 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 132 agc 105, measured sensitivity 31.30mm/rev, min -470% max 558% over 8288.2mm
3/23/2020, 3:27:57 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 133 agc 105, measured sensitivity 30.62mm/rev, min -261% max 383% over 2284.8mm
3/23/2020, 3:14:42 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 110, measured sensitivity 26.26mm/rev, min 31% max 104% over 176.4mm
M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 110, measured sensitivity 26.53mm/rev, min 31% max 105% over 97.2mm
3/23/2020, 3:09:30 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 110, measured sensitivity 26.77mm/rev, min -150% max 265% over 1755.0mm
3/23/2020, 3:03:35 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 26.54mm/rev, min -1% max 262% over 1614.2mm
3/23/2020, 3:02:22 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 26.44mm/rev, min -1% max 262% over 1467.0mm
3/23/2020, 2:56:46 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 26.58mm/rev, min -1% max 119% over 782.8mm
3/23/2020, 2:54:53 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 26.88mm/rev, min -1% max 121% over 557.8mm
3/23/2020, 2:54:01 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 27.10mm/rev, min -1% max 122% over 466.7mm
3/23/2020, 2:53:32 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 27.20mm/rev, min -1% max 122% over 436.3mm
3/23/2020, 2:52:13 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 27.60mm/rev, min -1% max 124% over 354.5mm
3/23/2020, 2:50:37 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 28.45mm/rev, min -1% max 128% over 254.7mm
3/23/2020, 2:50:18 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 28.70mm/rev, min -1% max 129% over 236.5mm
3/23/2020, 2:50:01 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 28.99mm/rev, min -1% max 130% over 218.3mm
3/23/2020, 2:49:53 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 29.15mm/rev, min -1% max 131% over 209.2mm
3/23/2020, 2:49:26 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 28.48mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 29.75mm/rev, min -1% max 134% over 181.9mm

The machine is a delta with smart effector.
Board: Duet WiFi 1.0 or 1.01
Firmware: RepRapFirmware for Duet 2 WiFi/Ethernet 2.05.1 (2020-02-09b1)
Duet WiFi Server Version: 1.23

[dc42]

Up to 110 is OK, however normal values are below 100. It looks as though the distance between the magnet and the sensor is a little too high (target is 0.25mm). Check that the screws holding the PCB down are not loose (caution: they are screwed into the plastic, so don't over-tighten them). If they are already tight, you could remove the 2 long screws to separate the two plastic parts and very slightly sand down the bottom surface of the top one (the one with the PCB attached).

[Nuffe]

@dc42 Thanks. The screws were quite loose. The two at the other end can be tightened.

Now with the first test the value was 99 but immediately started increasing. Is it normal for calibration data to change this much:

3/23/2020, 9:09:28 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 25.84mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 26.93mm/rev, min -74% max 294% over 506.0mm
3/23/2020, 9:07:10 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 25.84mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 129 agc 107, measured sensitivity 26.42mm/rev, min -7% max 104% over 229.3mm
3/23/2020, 9:06:14 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 25.84mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 130 agc 103, measured sensitivity 26.17mm/rev, min 67% max 103% over 
3/23/2020, 9:04:46 PM	M591 D0
Duet3D magnetic filament monitor with switch on input 3, disabled, sensitivity 25.84mm/rev, allow 60% to 140%, check every 3.0mm, version 3, mag 130 agc 103, measured sensitivity 25.85mm/rev, min 100% max 100% over 12.1mm

Now the ACG increased again, now 107 and print would have paused multiple times if the limits would be "production" limits.

[dc42]

The calibration accuracy at the start will be poor because of the small amount of filament extruded (12.1mm in your example), but improves as more filament is extruded. However, the range you got at the end is way too much. Please post a photo of your printer showing the filament monitor and the extruder.

[Nuffe]

@dc42

Sorry if my setup is the reason, it is hard to debug when one does not know what to expect. If the setup could be the reason, then it is could also be that micro switch casing. I'll test without that too.

The extruder is also new.